In a machine tool that machines objects to be machined (workpieces) having various shapes and dimensions, changing a workpiece to be machined may result in a workpiece having different shape and dimensions and may require that a member provided in the machine tool be changed, namely, may require a set-up change. For the set-up change resulting from this type of change in the workpiece, a predetermined member is needed, which is formed in accordance with the shape and the dimensions of the workpiece and which holds the workpiece, a machining tool, a shape measuring instrument and the like.
For example, a workpiece conveyance device, which holds the workpiece and conveys the workpiece between a workpiece replacement position and a workpiece machining position in the machine tool, is capable of reliably holding the workpiece in order to convey the workpiece to accurate positions. Thus, in the workpiece conveyance device, a gripper for holding the workpiece is formed in accordance with the shape and the dimensions of the workpiece, and various grippers are prepared having differing shapes and dimensions for each of the workpieces. Then, in the machine tool, when a workpiece to be machined is changed, in the workpiece conveyance device, the set-up change to a gripper corresponding to a workpiece after the change is performed.